The present research proposal is focused on designing non-covalently linked supramolecular porphyrin complexes suitable for mimicking the four-electron catalytic reduction of dioxygen to water at the active site of cytochrome c oxidase, and, also to develop new and efficient electrochemical sensors for dioxygen detection. Towards this goal, we propose to design, synthesize, and study ion-pair porphyrin dimers as well as supramolecular complexes of condensation polymer films of cyclodextrins hosting cobaltporphyrins. The electrodes modified with ion-pair porphyrin dimers are targeted as models for the active site of cytochrome c oxidase to perform a direct four-electron reduction of dioxygen to water at physiological pH conditions. Homonuclear porphyrin dimers, such as Co-Co, Fe-Fe or Mn-Mn will be prepared by using water soluble porphyrins bearing different charges on peripheral substituents. Either porphyrin of planar or non-planar rings will be utilized to adjust the inter-ring distance of a dimer. The electrodes modified with supramolecular complexes of condensation polymer films of cyclodextrin hosting cobaltporphyrins will be designed to serve as sensors for determination of dioxygen in solution. Both the neutral cyclodextrin polymer or anionic, i.e., carboxymethylated cyclodextrin polymer, film modified electrodes will be designed and fabricated to host cobaltporphyrins bearing either neutral, anionic or cationic charges on the ring periphery. By using various electroanalytical and spectroscopic techniques, first, we will focus on fundamental, e.g., mechanistic and kinetic aspects of the studied process. Conventional microelectrodes modified with supramolecular complexes of ion-pair dimers and cyclodextrins will subsequently be fabricated. Then, these electrodes will be tested for dedicated applications.